Companies can choose to build their own flexible workforce pools where you qualify as a talent. Joining a pool means that, along with a number of other talents, you are selected by a company to which they turn if they need staff. In these pools, the company publishes gigs that are only visible to the talents in the pool.
A pool is often created when there are certain requirements, so read the pool's description carefully and make sure you meet any qualification requirements before you apply.
Each time a pool matches your criteria, you receive a notification. Make sure you have a full profile to succeed in becoming accepted as a member to a pool.